That sound like a use case for DBIx::Class::DynamicSubclass.
Am Montag, den 24.08.2009, 17:14 +0200 schrieb John Napiorkowski:
> I know we all must often run into schema designs like the following:
>
> ## Column details removed for clarity
> package MyApp::Schema::Result::Gender; {
> use base 'MyApp::Schema::Result';
>
> __PACKAGE__->table('gender');
> __PACKAGE__->add_columns(qw/gender_id label/);
> }
>
> package MyApp::Schema::Result::Person; {
> use base 'MyApp::Schema::Result';
>
> __PACKAGE__->table('person');
> __PACKAGE__->add_columns(qw/person_id name fk_gender_id);
>
> __PACKAGE__->belongs_to(
> gender => 'MyApp::Schema::Gender',
> {'foreign.fk_gender_id' => 'self.fk_gender_id'}
> );
> }
>
> After all, this is type of normalization is a basic pattern. However, as far
> as I know we don't have a good system for installing the necessary data at
> populate time. What I mean here is that for the above database to be useful,
> you need some rows inserted into the 'gender' table, ie 'female', 'male',
> 'transgendered', etc.
>
> Things I've seen people do to work around this lack would include manually
> created SQL files to run post deployment, manually editing the sql generated
> by $storage->deploy, overloading deploy to run a set of ->create statements,
> or trying to use the Fixtures module.
>
> All the above solutions work, but have severe lacking. For example, all the
> solutions involving editing sql files fail to achieve the degree of database
> freedom DBIC offers out of the box. Additionally, by not having DBIC itself
> aware of the lookup information, you lose out on the chance to apply roles to
> your classes based on the lookup in a clear an easy manner. For example, I
> often have a 'state' table as a lookup normalization on a persons address.
> However, I also often have the need to apply special logic to people living
> in the state of California, since that state has a lot of special rules.
> Right now this usually manifests itself as a lot of ugly conditional logic.
> It would be really nice if DBIC itself could have enough awareness to apply
> components or roles at runtime when a row returned contain a particular
> lookup value.
>
> Lastly, it would be great if this system could hook cleanly into the DBIC
> framework for doing database diffs. That way if you had to alter something,
> like a list of Countries, for example, you'd get a head start on the
> generated sql between versions.
>
> So here's my first go at attempting to create some syntax for this. Yeah,
> there's a lot to do with it, but this is a start. It's possible we'd rather
> have the lookup data encapsulated in a different class, just to keep the the
> class files clean. Please your comments and suggestions very welcomed!
>
> package MyApp::Schema::Result::Gender; {
> use base 'MyApp::Schema::Result';
>
> __PACKAGE__->components('Lookup');
> __PACKAGE__->table('gender');
> __PACKAGE__->add_columns(
> gender_id => {
> data_type => 'varchar',
> size => '36',
> is_nullable => 0,
> },
> label => {
> data_type => 'varchar',
> size => '12',
> is_nullable => 0,
> },
> );
>
> __PACKAGE__->set_primary_key('gender_id');
> __PACKAGE__->uuid_columns('gender_id');
>
> __PACKAGE__->lookup_unique_label('label');
> __PACKAGE__->populate_lookup(
> ['lookup'],
> ['male'],
> ['female],
> ['transgendered'],
> ['unknown'],
> );
> }
>
> package MyApp::Schema::Result::Person; {
> use base 'MyApp::Schema::Result';
>
> __PACKAGE__->table('person');
> __PACKAGE__->add_columns(
> person_id => {
> data_type => 'varchar',
> size => '36',
> is_nullable => 0,
> },
> fk_gender_id => {
> data_type => 'varchar',
> size => '36',
> is_nullable => 0,
> },
> name => {
> data_type => 'varchar',
> size => '24',
> is_nullable => 0,
> },
> );
>
> __PACKAGE__->set_primary_key('person_id');
> __PACKAGE__->uuid_columns('person_id');
>
> __PACKAGE__->belongs_to(
> gender => 'MyApp::Schema::Gender',
> {'foreign.fk_gender_id' => 'self.fk_gender_id'}
> );
> }
>
>
> my $person = $schema->resultset('Person')->create({
> name='Joe Somebody',
> gender=>{label=>'male'},
> });
>
> my $female = $schema->resultset('Gender')->find_female;
> my $person = $schema->resultset('Person')->create({
> name='Mary Somebody',
> gender=>$female,
> });
>
>
>
>
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--
BR Alex
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